Air-cooled gun



s, 1943. H. sump/WE Em 2,337,8 0

AIR-COOLEQGUN Filed Jan. 6, 1942 M f mvENTo'R. BY QM ATTORNEYS PatentedDec. 28, 1943 TEN OFFlCE AIR-COOLED GUN Hubert Scott-Paine and RobertWilliam Jaggard, Hythe, England; said Jaggard assignor to saidScott-Paine 4 Claims.

This invention relates to air-cooled guns and more particularly to thattype of rapid firing gun having a jacket surrounding the barrel so as toprovide a space through which air under pressure is passed to eiiectcooling of the barrel.

More particularly the invention relates to means for controlling theflow of air through said space which is automatically actuated inaccordance with the temperature of a part of the gun which becomesheated when it is fired.

According to the invention there is provided, in a gun of the type setforth, an air inlet valve between a source of compressed air and thechammr between the barrel and the jacket, said valve beingthermostatically controlled by the expansion and contraction of a gunpart, to open the valve when cooling is required and to close the valvewhen adequate cooling has been efiected.

An object of the invention is to provide a novel type of valve forcontrolling the flow of compressed air.

Another object is to utilize the expansion and. contraction of the gunbarrel for the operation of the valve.

A further object is to utilize the expansion and contraction of a memberwhich is in close contact with the barrel, and is heated thereby, forthe operation of the valve.

The following is a description of two alternative forms of constructionaccording to this invention, reference being made to the accompanyingdrawing in which both Figures 1 and 2 are longitudinal sections throughthe gun barrel and cooling sleeve and a part of the breech casing andFigure 3 is an enlarged view of the valve shown in Figure 1.

In the construction shown in Fig. 1, a ribbed sleeve ll of aluminium orother good heat-conducting metal is forced on to the barrel II to assistin conducting heat away therefrom. A cooling jacket 12 spaced away fromit and surrounding it is located at one end in a recess l3 in a part ofthe breech casing M, having a close sliding fit therein so as to make asubstantially air-tight joint. At its forward end the jacket i2 issecured to the forward end of the barrel H by means of a spider I5 andlock-nut l6 so that the jacket partakes of the thermal expansionmovements of the forward end of the barrel relative to its rear end.

At its rear end the jacket i2 is provided with an inwardly directedflange formed with a valve rim [1. The rim extends axially to engage aflat face 18 formed on the breech casing M; with this arrangement thevalve provides an annular space [3 around the barrel to which compressedair at a high pressure, say of the order of 300 pounds per square inchor more, can be admitted through a passage 24. A manual shut off cook 25may be provided for closing the air line which connects with passage 24.

When the gun is operated, the temperature of the barrel ll rises and itexpands, but its temperature rises much more than that of the jacket l2so that the differential expansion of the two parts, which are heldtogether at the forward end of the barrel, results in the valve rim I!being lifted off its seat and admitting the compressed air to theinterior of the jacket. It is permitted to escape through suitableopenings in the spider 15, as shown in Fig. 1.

As shown in Fig. 3, the rim H which engages the seating H! on the breechcasing M is rounded ed at H! thus providing a Venturi-form dis chargepassage imposing a low resistance to the passage of the compressed air.The sudden expansion of the highly compressed air results in a fall oftemperature of the air which thereby is rendered more effective forcooling purposes.

It should also be notedthat by forming the valve rim on a flange on thejacket, a slight resilience is obtained permitting accurate closeseating of the valve when the gun is not in use.

In the construction shown in Fig. 2, the inner ribbed sleeve Illa whichis mounted on the gun barrel Ila is fitted less tightly to the barrelthan in the previous construction, so as to slide thereon, and ispositively clamped between the gun barrel and breech casing at its rearend. For example a flange 20 on the sleeve is engaged between a shoulder2| and a flange 22 in the breech part of the mechanism. The forward endof this sleeve carries a spider I5a, secured by a nut Him, to which theforward end of the jacket in is rigidly secured. The inner sleeve la isof aluminium or other material having a high coefficient of expansion,and since it gets hotter, when the gun is in use, than the externaljacket lZa, the rear-end of the jacket has a movement relative to therear end of the sleeve, or the flange 22 which it abuts, and thismovement is used to effect a valving of the air similar to thatdescribed above in connection with Figs. 1 and 3. This constructionprovides a greater valve opening than that previously described, for agiven temperature change, and therefore can be used with lowerair-supply pressures.

A particular advantage of this invention is that the flow of cooling aircontinues so long as the barrel or other part is at a higher temperaturethan the jacket, and thereby eifective cooling between bursts of firingis ensured; in the known auto-ejection air cooling systems in which aflow of air was introduced by the exhaust gases from the gun, the flowceased between the bursts of fire when the gun was not in use so thatadequate cooling could not be obtained.

The present invention therefore renders it possible to avoid the use ofthick and heavy barrels which have previously been used on account oftheir heat capacity or of making the barrels rapidly exchangeable whenhot. The invention is readily applied in the case of marine landinstallations where an adequate supply of compressed air is alreadyavailable so that no additional complications are introduced.

The foregoing specific embodiments of the invention herein described areto be taken merely as illustrative and the invention is not to beconstrued as limited to their specific details, which are obviouslysubject to modification without departing from the spirit of theinvention defined in the appended claims.

What is claimed is:

1. A thermostatic control for the flow of compressed air through achamber surrounding a gun barrel to effect cooling thereof comprising,gun having a. longitudinally extending member which becomes heated onfiring the gun, a breech casing secured to the rear end of said memberhaving a recess therein, a jacket surrounding said member and spacedtherefrom and forming said chamber, the forward end of said jacket beingsecured to the forward part of said member, the rear end of said jacketbeing slidably mounted in said recess, means for directing compressedair to said recess, and valving means in said recess controlling theflow of said air to said chamber and actuated by the differentialexpansion of said member and said jacket.

A thermostatic control for the flow of compressed air through a chambersurrounding a gun barrel to effect cooling thereof comprising, a gunhaving a longitudinally extending member which becomes heated on firingof the gun, a breech casing secured to the rear end thereof and havingan annular recess therein, a jacket surrounding said member and spacedtherefrom to form said chamber, the forward end of said jacket beingsecured to the forward part of said member, the rear end of said jacketbeing slidably mounted in said recess, an annular valve part carried bythe rear end of said jacket and coacting with a complementary valve parton said breech casing, said valve parts being adapted to open to admitair into said chamber upon differential expansion of said member andsaid jacket.

3. A thermostatic control for the flow of compressed air through achamber surrounding a gun barrel to efiect cooling thereof comprising, abarrel, a breech casing secure-d to one end thereof and having anannular recess adjacent the rear :portion of the barrel, a jacketsurrounding the barrel and having its forward end s cured to the forwardpart of the barrel and forming said chamber, the rear end of said jacketbeing slidably mounted in said recess, an annular valve part carried bythe rear end of said jacket and coacting with a complementary valve parton said breech casing, said valve parts being adapted to open to admitsaid compressed air inside the jacket upon differential expansion of thebarrel and jacket.

A thermostatic control for the flow of compressed air through a chambersurrounding a gun barrel to effect cooling thereof comprising, a barrel,a breech casing secured to one end thereof and having an annular recessadjacent the rear end of the barrel, a sleeve coaxial with the barreland capable of independent expansion relative thereto, a jacketsurrounding the barrel and the sleeve and having its forward end securedto the forward part of said sleeve and forming said chamber, the rearend of said jacket being slidably mounted in said recess, means forsecuring the rear end of said sleeve to said breech casing, an annularvalve part carried by the rear end of said jacket and coacting with acomplementary valve part on said breech casing, said valve parts beingadapted to open to admit said compressed air inside the jacket upondifierential expansion of the sleeve and jacket.

HUBERT SCOTT-PAINE. ROBERT WILLIAM JAGGARD.

